Antifriction composition



Patented Jan. 1, 1952 UNITED STATES ATNT OFFICE ANTIFRIC'IION CUE/{POSITION Calif., a joint venture No Drawing. Application July 20,1948, Serial No. 39,822

'5 Claims.

This invention relates generally to composi tions capable of providing bearing surfaces of low friction characteristics.

In the past various types of metals, alloys and compositions have been provided in an efiort to provide bearing surfaces of low. friction characteristics. Babbitt metal, which is an alloy containing tin, lead, copper and zinc, is one of the most common bearing alloys employed. It has many recognized limitations, including in particular its dependence upon oil lubrication, and the fact that it must be cast or machined to the form desired. Some antifriction bearing compo sitions are being made by powdered metallurgy technique, involving compressing metal powder followed by a sintering operation to secure a bond. This technique is relatively costly, and when metals such as lead and tin are introduced into such a composition, the sintering operation forms an alloy between them, so that they do not appear as individual ingredients in the final composition.

It is an object of the present invention to provide a new type of antifriction composition which has advantageous characteristics not possessed by other compositions now available.

Another object of the invention is to provide a composition of the above character in which metal ingredients, such as lead, zinc or tin, may be provided in the composition without forming an alloy between them, thus imparting desirable characteristics to the product.

Another object of the invention is to pro'vide a composition of the above character "which is adaptable for use in different ways, including the forming of bodies of considerable size, or its application as a relatively thin coating.

Additional objects of the-invention will appear from the following description in which the preferred embodiments'have been set forth in detail.

My composition consists of a number of divided solid ingredients, including graphite, and one or more divided metals, which are bonded together in a homogeneous mass by a thermally set synthetic resin. As will be presently explained such a composition can be provided in liquid form with a solvent, to form a coating, or it can be formed in masses of considerable size to the dimensions desired.

Assuming use of more than one metal in the composition, which is desirable, these metals remain as such in the final homogeneous composition, and are not sintered or alloyed together. Thus for example superior bearing characteristics can be obtained by the use of both lead and 2 tin, whereas in conventional compositions or'al loys it isimpossible to have these ingredients separately present.

The following is an example of a formula which can be used according to the present invention:

5 grams phenolformaldehyde resin in the form of a powder 0.4 gram flaked graphite 1;? grams lead in flaked form having a particle size of 320 mesh 1.7 gramscopper in flaked form and having a particle size of 320 mesh.

The above ingredients are homogeneously mixed together and may be molded under pressure and heat according to known plastic molding procedure, to form masses of the desired shape. Heat treatment is applied during or after molding to thermally set the resin, thus providing a body of considerable mechanical strength, which can be trimmed or shaped by known finishing methods, such as grinding.

A composition made as described above will aiford advantageous friction characteristics when used for example as a bearing for a rotating shaft. The graphite provides a dry lubricant, thus permitting the use of a minimum amount of oil on the bearing, or even permitting the bearing to operate dry with a minimum amount of injury and friction. The flaked lead provides a low melting point material which imparts favorable friction characteristics. In addition the presence of this metal, together with other metals such as copper, serves to impart relatively good heat conductivity to facilitate conduction of heat away from the friction surfaces.

In the above formula reference is made to the use of divided metals in flaked form. The flaked form of metal has been found to be superior to ordinary powdered metals, presumably because of the greater area which a flaked particle may present to the bearing area.

According to my observations, the thermally set resin forms a bonding material which provides the desired strength for the mass, and which more or less separates all of the particles from direct physical engagement with each other. It appears that the particles of graphite and metal, at the bearing surface, are exposed to forma part of the bearing area, although these particles are bonded by the synthetic resin and thus retained in place.

The use of finely divided flaked tin is likewise desirable in the composition such as described above. Thus a composition can be used containing lead, copper and tin, and having a formula as follows:

5 grams phenolformaldehyde resin in powdered form 0.4 grams flaked graphite 0.8 grams finely divided flaked lead 0.8 grams finely divided flaked copper 1.7 grams finely divided flaked tin.

In the last mentioned composition both the lead and tin have low melting points, and as is well known, these ingredients readily alloy to gether. In my composition however they retain their individual melting points and characteristics, thus imparting novel and desirable properties to the composition. Particularly with such a composition there are two materials of low melting point, whereby under conditions of rising temperature there is first a lubricating action due to thermal plasticity of the tin, and thereafter if the temperature further rises the lead becomes plastic. Thus lubricating action due to thermal plasticity of the metal particles is extended over a relatively wide temperature range, as distinguished from a very limited temperature range provided by other compositions and alloys.

I have also discovered that powdered silicon is a desirable ingredient to add to my composition. Use of this ingredient appears to decrease the coefiicient of friction, and to increase its resistance to wear. In general this ingredient can be added to the extent of say 5 to (by weight) of the remaining ingredients of the composition. Thus for the first mentioned formula I may add from 0.2 to 0.3 gram of powdered silicon, together with the resin, graphite, lead and copper. The second mentioned formula can be similarly modified.

In addition to its use to form bodies of considerable size, a composition such as described above can be applied to form relatively thin coatings on metal. Thus either of the two formulas specified above can be mixed with a suitable solvent, such as a mixture of ethyl, isopropyl and butyl alcohols, which dissolves the resin content, and which will provide a fluid mixture which can be sprayed, brushed on, or applied by dipping. After applying one or more coats, followed by air drying, such a coating'is cured by heating the same in a suitable oven to a temperature of the order of 300 F. or higher, to thermally set the resin. A composition of this type can be used to advantage to coat thin metal annuluses in sealing assemblies of the type disclosed in my Patent No.

2,428,041, in order to provide favorable wear and friction characteristics and as disclosed and claimed in my co-pending application, Serial No. 105,479, flied July 19, 1949. Likewise such a material can be applied to build up or repair worn bearing surfaces,

I claim:

1. A composition serving to provide a low friction bearing surface comprising essentially a thermally set synthetic resin having dispersed therein finely divided solids in flake form serving to reduce the surface friction characteristics of the composition, the solids including flaked copper, flaked lead, flaked tin and flaked graphite, the resin being the major constituent and the copper and lead being present in substantially equal proportions, the divided solids being substantially separated from direct physical engagement by the resin.

2. A composition serving to provide a low friction bearing surface comprising essentially a thermally set phenolformaldehyde resin having dispersed therein finely divided solids in flake form serving to reduce the surface friction characteristics of the composition, the solids including flaked graphite, flaked lead, and flaked copper, the proportions corresponding substantially to 5 grams of resin, 0.4 gram of flaked graphite, 1.7 grams of lead, and 1.7 grams of copper.

3. A composition serving to provide a low friction bearing surface comprising essentially a thermally set phenolformaldehyde resin having dispersed therein finely divided solids in flake form serving to reduce the surface friction characteristics of the composition, the solids comprising flaked graphite, flaked lead, flaked copper, and flaked tin, the proportions of the ingredients corresponding substantially to 5 grams of resin, 0.4 grams of flaked graphite, 0.8 gram of flaked lead, 0.8 gram of flaked copper, and 1.7 grams of flaked tin.

4. A composition serving to provide a low friction bearing surface comprising essentially a thermally set synthetic resin having dispersed therein finely divided solids serving to reduce the surface friction characteristics of the composition, the solids including flaked graphite, flaked copper, and flaked lead, the resin being the major constituent and the copper and lead being present in substantially equal proportions, the divided solids being substantially separated from direct physical engagement by the resin.

5. A composition as defined in claim 4 including a minor proportion of powdered silicon.

LAWRENCE G. SAYWELL.

REFERENCES CITED The following references are of record in the I file of this patent:

UNITED STATES PATENTS Number Name Date 1,969,041 Seabury et al. Aug. 7, 1934 2,159,935 Sanders May 23, 1939 2,326,000 Teeple Aug. 3, 1943 2,416,480 Henry et a1 Feb. 25, 1947 

4. A COMPOSITION SERVING TO PROVIDE A LOW FRICTION BEARING SURFACE COMPRISING ESSENTIALLY A THERMALLY SET SYNTHETIC RESIN HAVING DISPERSED THEREIN FINELY DIVIDED SOLIDS SERVING TO REDUCE THE SURFACE FRICTION CHARACTERISTICS OF THE COMPOSITION, THE SOLIDS INCLUDING FLAKED GRAPHITE, FLAKED COPPER, AND FLAKED LEAD, THE RESIN BEING THE MAJOR CONSTITUENT AND THE COPPER AND LEAD BEING PRESENT IN SUBSTANTIALLY EQUAL PROPORTIONS, THE DIVIDED SOLIDS BEING SUBSTANTIALLY SEPARATED FROM DIRECT PHYSICAL ENGAGEMENT BY THE RESIN. 